Cathode ray tube (CRT) displays, such as those commonly used in desk-top computer screens, function as a result of a scanning electron beam from an electron gun impinging on phosphors on a relatively distant screen. The electrons increase the energy level of the phosphors. When the phosphors return to their normal energy level, they release photons which are transmitted through the glass screen of the display to the viewer.
Field emission displays seek to combine the cathodoluminescent-phosphor technology of CRTs with integrated circuit technology to create thin, high resolution displays wherein each pixel is activated by its own set of cold cathode electron emitters. Flat panel display technology is becoming increasingly important in appliances requiring lightweight portable screens.
It is important in flat panel displays of the field emission cathode type that an evacuated cavity be maintained between the cathode electron emitting surface and its corresponding anode display face (also referred to as an anode, cathodoluminescent screen, display screen, faceplate, or display electrode.
There is a relatively high voltage differential (e.g., generally above 200 volts) between the cathode emitting surface (also referred to as base electrode, baseplate, emitter surface, cathode surface) and the display screen. It is important that electrical breakdown between the electron emitting surface and the anode display face be prevented. At the same time, the narrow spacing between the plates is necessary to maintain the desired structural thinness and to obtain high image resolution. The spacing also has to be uniform for consistent image resolution, and brightness, as well as to avoid display distortion, etc. Uneven spacing is much more likely to occur in a field emission cathode, matrix addressed flat vacuum type display than in some other display types because of the high pressure differential that exists between external atmospheric pressure and the pressure within the evacuated chamber between the baseplate and the faceplate. The pressure in the evacuated chamber is typically less than 10.sup.-6 torr. Accordingly, the term "vacuum" is meant to refer to negative pressures of this type.
Contamination by unwanted, residual gases in the vacuum chamber will effect the performance of the display. Residual gases may even cause destructive arcing in the display. For example, oxygen molecules trapped in the evacuated chamber must be immobilized. The wire bonded "getters" of the present invention function to precipitate the oxygen molecules out of the evacuated atmosphere, thereby minimizing the effect such oxygen molecules will have on the functioning of the display, and consequently the image produced thereon.